The American soldier who allegedly shot and killed 16 men, women and children in two Afghan villages was from an Army base outside Tacoma, Washington. The Army/Air Force installation, Joint Base Lewis-McChord, is one of the biggest in the military.

It's also, as NPR's Martin Kaste reports, one of the most troubled.

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MARTIN KASTE, BYLINE: So far, the prevailing reaction to the news from Afghanistan has been disbelief.

DENNIS WHITE: There had to be a reason for that (unintelligible). He had a mental breakdown over there or something.

KASTE: Dennis White is swinging a sign for a tax service on the commercial strip just outside the base gates. He lives around here, talks to soldiers every day, and he worries about them.

WHITE: Uncle Sam really needs to take a psych evaluation of all its troops and soldiers that's going over there, that's been over there.

KASTE: Soldiers from Joint Base Lewis-McChord have generated a lot of disturbing headlines lately. Most notorious was the so-called Kill Team, a group of soldiers court-martialed for killing Afghan civilians for sport. There's also been violence here at home: dramatic cases of soldiers torturing or killing family members, suicides, and most recently the shooting death of a Mount Rainier park ranger by a former soldier who'd been discharged for misconduct. And now a massacre.

JORGE GONZALEZ: First thing that went through my mind is, I wonder if this person is from Joint Base Lewis-McChord.

KASTE: Jorge Gonzalez is an Army vet turned anti-war activist. He runs a coffee shop just outside the base. He admits you find problems like this on any military installation, but he believes something deeper is going on here.

GONZALEZ: It's mysterious. It could be anything from lack of treatment to just purposefully denying soldiers their right take care of themselves.

KASTE: There's been a lot of attention recently on the base hospital, where soldiers complained that the medical staff denied them post traumatic stress disorder diagnoses to save money. Two hundred and eighty-five of the hospital's patients have now won the right to be re-evaluated for PTSD.

Specialist Andrew Baker, who works on post as a dental assistant, says Lewis-McChord's bad reputation is spreading. He even got a call about it recently from his father, an Army Sergeant-Major based in Georgia.

SPECIALIST ANDREW BAKER: He's a career counselor so he sees the reports from all the different posts. And he was asking why there's so much bad stuff going on on JBLM. Who was asking why there's so many soldiers getting in trouble. I didn't have answer for him.

KASTE: Officials with the base wouldn't comment about the shooting rampage or about the concerns about potential discipline or mental health problems at Lewis-McChord.

Washington Congressman Rick Larsen, who serves on the House Armed Services Committee, says he is not ready to single the base out.

REPRESENTATIVE RICK LARSEN: I think it's a bit of stretch to say there's something about Joint Base Lewis-McChord, as opposed to just the fact that the missions that people serve in are tough. And we need to be sure that they have - these men and women have the support that they need when they come home.

KASTE: And many do need support. Brigades from Lewis-McChord have seen multiple deployments to some of past decade's toughest war zones.

But despite all that stress, Lieutenant Travis Morgato says he still can't understand why a soldier would do this.

LIEUTENANT TRAVIS MORGATO: I know a lot of people in the Army and I just - I don't know - I know a lot of people who've done multiple deployments. And, you know, it's rough for them but they always come back still level-headed that I've seen.

KASTE: Morgato is heading out on his first deployment in a few weeks. He's going to Afghanistan.

MORGATO: It's definitely going to be a little bit crazy, I think, when I get there now.